Allow users to customize the internal ObjectMapper created by GenericJackson2JsonRedisSerializer.

We now allow the internally created Jackson ObjectMapper to be customized and further configured after construction of the GenericJackson2JsonRedisSerializer when a user does not explicitly provide a custom ObjectMapper during construction. Even when providing a custom ObjectMapper, not all configuration applied by the GenericJackson2JsonRedisSerialzier (such as (standard) type resolution) to the internal ObjectMapper would get applied to the user-provided ObjectMapper as well.

Closes #2601

Author: jxblum

src/main/java/org/springframework/data/redis/serializer/GenericJackson2JsonRedisSerializer.java

@@ -18,6 +18,7 @@
 import java.io.IOException;
 import java.io.Serial;
 import java.util.Collections;
+import java.util.function.Consumer;
 import java.util.function.Supplier;
 
 import org.springframework.cache.support.NullValue;
@@ -196,12 +197,22 @@ private Supplier<String> newTypeHintPropertyNameSupplier(ObjectMapper mapper, @N
 		return typeHintPropertyName != null ? () -> typeHintPropertyName
 			: Lazy.of(() -> defaultTypingEnabled.get() ? null
 					: mapper.getDeserializationConfig().getDefaultTyper(null)
-						.buildTypeDeserializer(mapper.getDeserializationConfig(),
-								mapper.getTypeFactory().constructType(Object.class), Collections.emptyList())
+							.buildTypeDeserializer(mapper.getDeserializationConfig(),
+									mapper.getTypeFactory().constructType(Object.class), Collections.emptyList())
 						.getPropertyName())
 					.or("@class");
 	}
 
+	/**
+	 * Gets the configured {@link ObjectMapper} used internally by this {@link GenericJackson2JsonRedisSerializer}
+	 * to de/serialize {@link Object objects} as {@literal JSON}.
+	 *
+	 * @return the configured {@link ObjectMapper}.
+	 */
+	protected ObjectMapper getObjectMapper() {
+		return this.mapper;
+	}
+
 	@Override
 	public byte[] serialize(@Nullable Object source) throws SerializationException {
 
@@ -248,11 +259,33 @@ public <T> T deserialize(@Nullable byte[] source, Class<T> type) throws Serializ
 
 		try {
 			return (T) reader.read(mapper, source, resolveType(source, type));
-		} catch (Exception ex) {
-			throw new SerializationException("Could not read JSON: " + ex.getMessage(), ex);
+		} catch (Exception cause) {
+			String message = String.format("Could not read JSON:%s ", cause.getMessage());
+			throw new SerializationException(message, cause);
 		}
 	}
 
+	/**
+	 * Builder method used to configure and customize the internal Jackson {@link ObjectMapper} created by
+	 * this {@link GenericJackson2JsonRedisSerializer} and used to de/serialize {@link Object objects}
+	 * as {@literal JSON}.
+	 *
+	 * @param objectMapperConfigurer {@link Consumer} used to configure and customize the internal {@link ObjectMapper};
+	 * must not be {@literal null}.
+	 * @return this {@link GenericJackson2JsonRedisSerializer}.
+	 * @throws IllegalArgumentException if the {@link Consumer} used to configure and customize
+	 * the internal {@link ObjectMapper} is {@literal null}.
+	 */
+	public GenericJackson2JsonRedisSerializer configure(Consumer<ObjectMapper> objectMapperConfigurer) {
+
+		Assert.notNull(objectMapperConfigurer,
+			"Consumer used to configure and customize ObjectMapper must not be null");
+
+		objectMapperConfigurer.accept(getObjectMapper());
+
+		return this;
+	}
+
 	protected JavaType resolveType(byte[] source, Class<?> type) throws IOException {
 
 		if (!type.equals(Object.class) || !defaultTypingEnabled.get()) {

src/test/java/org/springframework/data/redis/serializer/GenericJackson2JsonRedisSerializerUnitTests.java

@@ -17,8 +17,14 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.when;
 import static org.springframework.test.util.ReflectionTestUtils.getField;
 import static org.springframework.util.ObjectUtils.nullSafeEquals;
@@ -32,6 +38,7 @@
 import java.util.Objects;
 import java.util.UUID;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
 
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
@@ -412,6 +419,33 @@ void deserializesJavaTimeFrimBytes() {
 		assertThat(serializer.deserialize(source, WithJsr310.class).myDate).isEqualTo(java.time.LocalDate.of(2022,9,2));
 	}
 
+	@Test // GH-2601
+	public void internalObjectMapperCustomization() {
+
+		GenericJackson2JsonRedisSerializer serializer = new GenericJackson2JsonRedisSerializer();
+
+		com.fasterxml.jackson.databind.Module mockModule = mock(com.fasterxml.jackson.databind.Module.class);
+
+		ObjectMapper mockObjectMapper = mock(ObjectMapper.class);
+
+		Consumer<ObjectMapper> configurer = objectMapper -> mockObjectMapper.registerModule(mockModule);
+
+		assertThat(serializer.configure(configurer)).isSameAs(serializer);
+
+		verify(mockObjectMapper, times(1)).registerModule(eq(mockModule));
+		verifyNoMoreInteractions(mockObjectMapper);
+		verifyNoInteractions(mockModule);
+	}
+
+	@Test // GH-2601
+	public void configureWithNullConsumerThrowsIllegalArgumentException() {
+
+		assertThatIllegalArgumentException()
+			.isThrownBy(() -> new GenericJackson2JsonRedisSerializer().configure(null))
+			.withMessage("Consumer used to configure and customize ObjectMapper must not be null")
+			.withNoCause();
+	}
+
 	private static void serializeAndDeserializeNullValue(GenericJackson2JsonRedisSerializer serializer) {
 
 		NullValue nv = BeanUtils.instantiateClass(NullValue.class);